Yahoo! is to commence a search for a new chief executive after Jerry Yang announced that he is stepping down from the post.The 40-year-old will revert to his former role as chief Yahoo! once a successor has been found. He will remain a member of the Yahoo! board.Mr Yang was subjected to criticism from shareholders earlier this year after he rejected Microsoft's takeover bid, a move that sparked speculation over whether he would be able to stay at the company for much longer.According to Michael McGuire of Gartner, Mr Yang's announcement came as no surprise considering the circumstances, the AFP reports.In a statement, Mr Yang commented: "Having set Yahoo! on a new, more open path, the time is right for me to transition the chief executive role and our global talent to a new leader."Mr Yang co-founded Yahoo! in 1994 and took over the role of chief executive in June last year following the departure of Terry Semel.